In many industrial processes it is desirable to separate a finely dispersed phase from the liquid in which it is dispersed. The ease of this separation can be enhanced if the fine particles flocculate to form large aggregates. This flocculation can be made to occur by employing a polymeric additive that initially dissolves or disperses in the liquid, but then precipitates from solution while interacting with the particulates. Precipitation of the polymer can be induced by chemical or physical factors in the environment in which the polymer is dissolved or dispersed. Flocculation of particles results when the polymer coated particles collide. Thus, the physical or chemical factors in the environment need not be changed for the polymer to precipitate.
The present invention teaches that in a flocculation process of coke fines and catalyst fines from a solution by the use of a flocculating agent which is polystyrene or an unneutralized or neutralized sulfonated polystyrene, the flocculation process is improved by the addition of an antisolvent. The sulfonated polystyrene interacts with the catalyst fines or coke fines and a precipitate is formed of the sulfonated polystyrene and catalyst fines or coke fines upon the addition of an antisolvent. Flocculation of other fines, such as synthetic fuels, shale and coal fines, can be promoted by the use of the sulfonated polystyrene as a flocculating agent.